Our brains are amazing organs. They’re capable of solving highly complex problems and achieving incredible feats. But the brain isn’t perfect. Despite its many strengths, it doesn’t take much to completely confuse it. Case in point: The Stroop effect.

The Stroop effect—named after John Ridley Stroop, who first wrote about it in a psychology paper—illustrates what happens when the brain is trying to process conflicting streams of information. Specifically, the test that produces the effect involves naming the color a word is printed in when the word itself is the name of a different color. (Example: seeing the word “red” in a blue font and saying “blue.") Reading words is easy, naming colors on their own is a bit harder—and when those two things conflict, the brain is sent into a bit of a tizzy.

You can watch the folks over at Science World in British Columbia above as they take the Stroop test, and play along to test your own mental flexibility. Be prepared to feel flustered.